add legend to traces - allow legendgroup to group inside each legend

Author: archmoj

src/components/legend/defaults.js

@@ -10,7 +10,7 @@ var basePlotLayoutAttributes = require('../../plots/layout_attributes');
 var helpers = require('./helpers');
 
 function getLegendName(id) {
-    return 'legend' + id;
+    return 'legend' + (id || '');
 }
 
 function groupDefaults(id, layoutIn, layoutOut, fullData) {
@@ -157,15 +157,15 @@ function groupDefaults(id, layoutIn, layoutOut, fullData) {
 
 module.exports = function legendDefaults(layoutIn, layoutOut, fullData) {
     var i;
-    var groups = [''];
+    var legends = [0];
 
     for(i = 0; i < fullData.length; i++) {
-        Lib.pushUnique(groups, fullData[i].legendgroup);
+        Lib.pushUnique(legends, fullData[i].legend);
     }
 
     layoutOut._legends = [];
-    for(i = 0; i < groups.length; i++) {
-        var id = groups[i];
+    for(i = 0; i < legends.length; i++) {
+        var id = legends[i];
         var name = getLegendName(id);
         if(id && !layoutIn[name]) continue;
 

src/components/legend/draw.js

@@ -28,9 +28,10 @@ module.exports = function draw(gd, opts) {
     if(opts) {
         drawOne(gd, opts);
     } else {
-        var legendGroups = gd._fullLayout._legends;
-        for(var i = 0; i < legendGroups.length; i++) {
-            drawOne(gd, gd._fullLayout['legend' + legendGroups[i]]);
+        var legends = gd._fullLayout._legends;
+        for(var i = 0; i < legends.length; i++) {
+            var legendObj = gd._fullLayout['legend' + (legends[i] || '')];
+            drawOne(gd, legendObj);
         }
     }
 };

src/components/legend/get_legend_data.js

@@ -16,8 +16,8 @@ module.exports = function getLegendData(calcdata, opts, hasMultipleLegends) {
     var maxNameLength = 0;
     var i, j;
 
-    function addOneItem(legendGroup, legendItem) {
-        if(hasMultipleLegends && legendGroup !== opts._id) return;
+    function addOneItem(legendId, legendGroup, legendItem) {
+        if(hasMultipleLegends && legendId !== opts._id) return;
 
         // each '' legend group is treated as a separate group
         if(legendGroup === '' || !helpers.isGrouped(opts)) {
@@ -40,6 +40,7 @@ module.exports = function getLegendData(calcdata, opts, hasMultipleLegends) {
         var cd = calcdata[i];
         var cd0 = cd[0];
         var trace = cd0.trace;
+        var lid = trace.legend;
         var lgroup = trace.legendgroup;
 
         if(!inHover && (!trace.visible || !trace.showlegend)) continue;
@@ -51,7 +52,7 @@ module.exports = function getLegendData(calcdata, opts, hasMultipleLegends) {
                 var labelj = cd[j].label;
 
                 if(!slicesShown[lgroup][labelj]) {
-                    addOneItem(lgroup, {
+                    addOneItem(lid, lgroup, {
                         label: labelj,
                         color: cd[j].color,
                         i: cd[j].i,
@@ -64,7 +65,7 @@ module.exports = function getLegendData(calcdata, opts, hasMultipleLegends) {
                 }
             }
         } else {
-            addOneItem(lgroup, cd0);
+            addOneItem(lid, lgroup, cd0);
             maxNameLength = Math.max(maxNameLength, (trace.name || '').length);
         }
     }

src/plots/attributes.js

@@ -32,6 +32,17 @@ module.exports = {
             'trace is shown in the legend.'
         ].join(' ')
     },
+    legend: {
+        valType: 'number',
+        dflt: 0,
+        min: 2,
+        editType: 'style',
+        description: [
+            'Sets the legend id to show this trace in.',
+            'If *0* (the default value), it refers to `layout.legend`.',
+            'If *2*, it refers to `layout.legend2`, and so on.'
+        ].join(' ')
+    },
     legendgroup: {
         valType: 'string',
         dflt: '',

src/plots/plots.js

@@ -1321,6 +1321,7 @@ plots.supplyTraceDefaults = function(traceIn, traceOut, colorIndex, layout, trac
                 'showlegend'
             );
 
+            coerce('legend');
             coerce('legendwidth');
             coerce('legendgroup');
             coerce('legendgrouptitle.text');

src/traces/parcats/attributes.js

@@ -197,6 +197,7 @@ module.exports = {
     customdata: undefined,
     hoverlabel: undefined,
     ids: undefined,
+    legend: undefined,
     legendgroup: undefined,
     legendrank: undefined,
     opacity: undefined,

test/image/mocks/zz-multi-legends.json

@@ -11,15 +11,15 @@
         },
         {
             "y": [3],
-            "legendgroup": "2"
+            "legend": 2
         },
         {
             "y": [4],
-            "legendgroup": "3"
+            "legend": 3
         },
         {
             "y": [5],
-            "legendgroup": "3"
+            "legend": 3
         }
     ],
     "layout": {